Bluetooth: hci_uart: Remove redundant assignment to fw_ptr

The variable fw_ptr is assigned a value that is not read and the same value
is assigned in the patch goto. The assignment is redundant and can be
removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Nigel Christian <nigel.l.christian@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>